Growth and characterization of gallium nitride nanostructures microstructures on sapphire gallium nitride and graphene substrates by chemical vapour deposition

Abstract

Among the III Nitride semiconducting materials Gallium Nitride GaN has a special place by virtue of its unusual properties like direct bandgap high thermal conductivity and high melting point Its ability to form ternary alloys with indium and aluminium makes it possible to tune the bandgap between 0 7 to 6 2 eV which covers a broad range of spectrum from infrared to ultraviolet region These qualities make GaN more suitable for opto electronics applications even in harsh conditions Usually GaN is hetero epitaxially grown on non native substrates Sapphire is most commonly preferred for the epitaxial growth of GaN The hexagonal crystal structure of sapphire which is similar to that of GaN and low cost are the main reasons for preferring sapphire substrates despite their high lattice mismatch with GaN This mismatch tends to induce defects and dislocations thereby degrading material properties and device performances when fabricated To ovecome these deficiencies and also to efficiently utilize the material properties of GaN it is beneficial to grow GaN in the form of Nanostructures NSs rather than as epilayers One dimensional NSs have attracted large scale study due to their potential for application in electronic and optical devices Researchers have attempted to synthesize NSs by employing various methods of growth The reasons for preference of GaN NSs are its outstanding size effects vast surface to volume ratio ability to grow on lattice and thermal mismatched substrates and tolerance towards harsh environments newline